The huge drop at the box office for the second week of Ridley Scott's Prometheus is pretty easily explained: People don't particularly want to see it.
Fanboys, however, who had inexplicably based their whole summer around this film--well, this and The Dark Knight Rises, and I'll get to that--feel compelled to offer their own tortured explanations for its less than stellar grosses. Audiences just didn't get it, they say, what with it being so sophisticated and all, or its sophistication (they love that word, and will use it even when it doesn't apply) was somehow a bad fit for a summer movie release, thus ignoring that Alien, the very film to which Prometheus is a prequel (although don't get them started on the whole prequel thing, either) was, of course, a summer release, and was instantly iconic in a way the new film could never hope to be.
The belief that this would be a good movie despite all evidence to the contrary is a hallmark of fanboy behavior. Harder to explain is why they thought Prometheus would be any good. I love Alien as much as anybody, and admire Ridley Scott's direction of it, but he was clearly not the dominant voice in that film's creation. It was screenwriter Dan O'Bannon who suggested bringing designer H.R. Giger on board, and everything so well-remembered about the film--the Space Jockey, the row of eggs, the face-hugger and, of course, the title character--seemed to have sprung fully-formed from Giger's head. Scott filmed it all well, sure, and he assembled a great cast, but O'Bannon's script and Giger's designs are the reason the film is so beloved.
But to the fanboys, all that mattered was that the director of Alien was returning to the same universe. Never mind that he hadn't made a wholly satisfying movie since...well, since Alien, actually, and that was over thirty years ago. A long string of dismal work (Black Rain, 1492, Robin Hood) gave no reason to believe this was anything but a desperation move, but Fan Nation was out in full force. Mere mentions of the film online, in any forum whatsoever, were met with unasked-for comments promising the film would be great--presumably because Harry Knowles said so--and after it came out, Fan Nation threatened to eat itself, as rabidly pro-and anti-Prometheus factions popped up to argue the merits of a film that really can't support the attention..
But hey, great news. Soon this will all be behind us, as The United States Of Geekdom will turn its easily-provoked focus to The Dark Knight Rises. Fans have met even the most insignificant news items about this film with orgasmic glee--It has a running time of over two-and-a-half hours! Epic!--so by mid-July, some sort of official consensus will have formed around Prometheus, and even the fanboys themselves will be left wondering why they made such a big deal about it in the first place.